The primary goal of the Clinical Core is to help validate the translational relevance by which inflammation and alterations in cellular metabolism contribute to PH in the animal models of Projects 1-3. This important link will advance the clinical relevance of the uncovered mechanisms, and will be the initial step towards actuating novel diagnostic and therapeutic strategies from these discoveries for patients with PAH. As outlined in the specific aims and tasks of the Core, we will facilitate this goal by providing extensively phenotyped and carefully categorized PAH patient and control samples (peripheral blood cells, plasma, serum, lung tissue, RNA and DNA) to the 3 Projects of the PPG. We will collect and record serial and longitudinal phenotypic data on enrolled prospective patients, including clinical, hemodynamic and advanced echocardiographic assessment of right ventricular function. We will assist in study design and perform the biostatistical analysis for all three Projects. The patient samples will consist of the following 3 cohorts: 1) Blood samples from patients and carefully matched controls followed in the Pulmonary Hypertension and Rheumatology clinics at the University of Colorado (prospective studies), 2) Lung tissue from the Pulmonary Hypertension Breakthrough Initiative (PHBI) and 3) Serum, plasma, RNA, DNA and lung tissue from the PVD Biorepository at the University of Colorado (retrospective studies). The samples will be collected from 4 distinct patient populations: 1) Connective tissue disease associated PAH (CTD-PAH), 2) Idiopathic pulmonary arterial hypertension (IPAH) and 3) CTD without PAH (CTD w/o PAH) and 4) Normal Controls. The clinical core is perfectly situated to support the translational research goals of the proposed PPG. We have assembled a group of investigators expert in the performance of studies such as those proposed within the Projects. Our mission is greatly facilitated by leveraging clinical resources required for patient care (diagnosis and follow-up), the current resources of the University of Colorado PVD center including the biorepository and by the ongoing funded PHBI. The Clinical Core will work closely with the Project leaders and the Pathology/Flow Cytoemtry Core to meet these goals.